Eron Adoberg

Influence of Laser Hardening to the Sliding Wear Resistance of the PVD (Al,Ti)N-G and nACo® Coatings

In the present article, the laser hardening of the carbon steel C45, previously coated by the physical vapour deposition (PVD) process, is studied. The (Al,Ti)N-G and nACo® (nc-AlxTi1-xN/α-Si3N4) coatings were applied. Nd:YAG laser with the laser beam power density of 1945 W/cm2 and scan speed of 300 mm/min was used for hardening process. Laser hardening lead to the formation of hardened layer under both coatings, consisting of austenite and ferrite. The approximate depth of the hardened layer and maximal microhardness was approximately 0.2 mm and 955 HV0.05 and 0.1 mm and 520 HV0.05 in the case of the (Al,Ti)N-G and the nACo® coating, respectively. After laser hardening the sliding wear of the (Al,Ti)N-G coating decreased by 1.25 times and of the nACo® coating by 1.05 times.

Impact and Sliding Wear Properties of Single Layer, Multilayer and Nanocomposite Physical Vapour Deposited (PVD) Coatings on the Plasma Nitrided Low-Alloy 42CrMo4 Steel

Current paper handles the comparison of impact wear and sliding wear properties of the hard PVD single layer TiN and Ti(C,N), multilayer (Ti,Al)N and nanocomposite FiVIc® coatings on the plasma nitrided low-alloy 42CrMo4 steel. All the studied coatings demonstrated a relatively high impact wear resistance at the low (104) and medium (105) number of impacts, however, all the studied coatings vanished at the high number of impacts (106). Most extensive wear among the coatings during the sliding wear test was observed for the (Ti,Al)N coating, the FiVIc® showed the least extensive wear; the most extensive wear of the counterbody (hardened steel ball) was registered for the (Ti,Al)N coating, the lowest – for the FiVIc® and Ti(C,N) coatings. The principle wear mechanism of coatings was tribooxidation and mild abrasion, of the counterbody – plastic deformation

Evaluation of Residual Stresses in PVD Coatings by means of Tubular Substrate Length Variation

The aim of the study was to determine macroscopic residual stresses in PVD coatings. The device for measurement of the length of the substrate was improved, where a change in tube length was reduced to the deflection of the middle cross-section of the elastic element whose deformation was measured by four strain gauges. The formulas for calculation of residual stresses are presented. For comparison a unilateral coating was deposited on a vertically fixed plate using the conventional curvature method. As an application, residual stresses in hard PVD TiAlN coatings were investigated. The microstructure and thickness of the studied coatings were investigated by means of scanning electron microscopy (SEM) in Zeiss EVO MA-15. The mean values of compressive residual stresses determined by both methods, for the studied coatings, were very high (3.1-6.5 GPa), irrespective of coating thickness, and practically equal with the measurement uncertainty of the method. The developed tube length variation method is reliable and applicable for determination of residual stresses in PVD coatings. Introduction Physical Vapour Deposition (PVD) coatings are used inter alia for blanking, punching and cutting applications and can be deposited both on plain and more complex surfaces [1, 2]. It is wellknown that residual stresses arising in coatings during the deposition process have an important effect on the service life of the coating through influencing its mechanical and tribological properties and adhesion. The aim of the study was to determine macroscopic residual stresses in coatings vapoured on a vertically fixed cylindrical surface, using the deformation method, through measurement of the longitudinal length variation of the thin-walled tube, as well as to validate the results obtained with the conventional curvature method using the plate as the substrate. One batch of vertically fixed plates was prepared by depositing a unilateral coating on the front surface and the other batch of plates, by depositing it on the back surface. Thus a considerable amount of the vapoured target material was deposited on the fixing device as well [3]. On the other hand, using the tubular substrate, most of the coating was deposited on the outer surface of the tube (a small part of the coating was deposited on the nozzle) it is possible to estimate the values of residual stresses in coatings on cylindrical surfaces (e.g. cutting tools [4]). The measuring device for determination of the longitudinal length change of the substrate was improved (Fig. 3), where tube length variation was reduced to the deflection of the middle crosssection of the elastic element whose deformation was measured by four strain gauges [5]. As an example of application, residual stresses were measured in hard PVD TiAlN coatings which are Residual Stresses 2018 – ECRS-10 Materials Research Forum LLC Materials Research Proceedings 6 (2018) 131-136 doi: http://dx.doi.org/10.21741/9781945291890-21 132 most widely used for cutting tools [4]. Also the microstructure and thickness of the studied coating were investigated by means of scanning electron microscopy. Evaluation of Residual Stresses in the Coating Plates (Fig. 1b) are only deposited from one side and should be placed gripped with a claw in the fixing device made of carbon steel [3]. Depending on the deflection of the plate, modified Stoney’s formula will account for biaxial stresses [6]. In order to prevent deposition of the coating on the cross-section of the tube ends, they were closed by the nozzle (Fig. 1a); at the same time, the tube was vertically fixed, by the lower nozzle, to the rotary table of the chamber and was simultaneously rotated around its axis. a)

Evaluation of Residual Stresses in PVD Coatings by Means of Strip Substrate Length Variation and Curvature Method of Plate Substrate

The aim of the study was to determine macroscopic residual stresses in Physical Vapor Deposits (PVD) coatings through measurement of the length variation of the strip substrates coated on both sides. The length change of the strip was reduced to the deflection of the middle cross-section of the elastic element and was recorded by four strain gauges. For validating the obtained results, the conventional curvature method was used. As an application, residual stresses in hard AlCrN PVD coatings were investigated. The coatings were nanolayered to achieve better coating toughness for blanking and punching applications. The steel strips and steel plates with two thicknesses were used as the substrate. The values of the compressive residual stresses, determined by both methods for the investigated coatings, were very high (3.3 -3.6 GPa) independent of coating thickness and practically equal within the measurement uncertainty of the method. Good agreement between the experimental results obtained with both methods suggests that the presented method, strip length variation, is applicable for determination of residual stresses in coatings. Compressive stresses in coatings are desirable as they strengthen the coating.

Evaluation of Residual Stresses in PVD Coatings by Means of the Curvature Method of Plate

Physical Vapor Deposition (PVD) coatings are primarily designed for metal cutting tools operating in extreme machining and blanking conditions. Residual stresses arising during coating deposition exert an important effect on the service life of the coating through influencing mechanical and tribological properties and adhesion. To determine macroscopic residual stresses, the conventional curvature method was used. As an application, residual stresses in four aluminum based PVD hard coatings, i.e. AlTiN, AlTiSiN, AlCrN, and AlCrSiN, were investigated in the presence of the Ti adhesion layer. Nickel steel plates and steel plates were used as the substrate. Residual stresses were compressive and high (3.0-7.5 GPa) in all coatings. Compressive stresses in coatings are desirable in cohesive tool damage as they strengthen the coating. The values of residual stresses were not significantly dependent on the angle of plate placement (parallel (0°), inclined (45°) and perpendicular (90°)) in relation to the PVD cathode in the deposition chamber. The magnitude of residual stresses is influenced by intrinsic strain at layer growth rather than by thermal stress.

Evolution of TiN Coating Surface Roughness during Physical Vapor Deposition on High Speed Steel Substrate

TiN coatings with different thickness were prepared by arc ion plating (AIP) physical vapor deposition (PVD) on high speed steel (HSS) substrates. TiN coatings surface roughness was investigated by atomic force microscopy (AFM) and 3D optical profilometry and growth kinetics was described using scaling exponents β and α. The growth exponent β is 0.91-1.0 and the roughness exponent α is 0.77-0.81. Due to relatively high value of the exponent α, the surface diffusion is likely predominant smoothening mechanism of TiN growth.